The following relates generally to wireless communication, and more specifically to slot format indicator (SFI) in frequency division duplexing (FDD).
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth generation (4G) systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform-spread-OFDM (DFT-S-OFDM). A wireless multiple-access communications system may include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).
Certain wireless communication systems may be configured to support time division duplexing (TDD) SFI indication. Generally, the TDD SFI may be a bit (or set of bits) that correspond to a TDD table. In some aspects, the TDD table may have a plurality of rows, where each row corresponds to a slot format for a slot. Each column of the TDD table may correspond to a symbol of the slot. Generally, each row may be configured with an indication, for each symbol, of whether that symbol is configured for uplink communications (U), for downlink communications (D), or is unknown (X). Accordingly, a UE receiving the TDD SFI will use the SFI to access the TDD table and determine how each symbol is configured for the slot.